Project Atomic-Nulecule
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This document discusses Project Atomic and multi-container application packaging. It introduces Atomic Host, an optimized operating system for containers; Nulecule, a specification for describing multi-container applications; and Atomic App, a tool for installing applications defined by Nulecule specifications. Key components of Atomic Host like rpm-ostree and Cockpit are also summarized. The document encourages getting involved in the open source projects and provides references for learning more.
Project Atomic-Nulecule
- 1. Project Atomic And Multi-Container Application Packaging Lalatendu Mohanty Senior Software Engineer @ Red Hat
- 3. Atomic Host ● It is not a new GNU/Linux distribution. ● Framework to create an OS from RHEL, CentOS and Fedora. ● Optimized for Linux containers.
- 4. Why Atomic Host? ● Our expectation from an OS is not same anymore. – Pets vs Cattle. ● Updating and maintaining the system should be easy. ● It needs to be more secure than the traditional OS
- 5. Atomic hosts comprises of ● Rpm-ostree ● Cockpit ● Kubernets ● /usr/bin/atomic ● Docker
- 6. OSTree “OSTree was born to help implement a continuous delivery model for operating systems. One can be a lot more confident in updating systems if one knows that a reliable rollback system is always available.” COLIN WALTERS Senior Software Engineer, Inventor of OSTree Red Hat
- 7. rpm-ostree ● Git for operating systems. ● Update methods of containers and applied them to operating system. ● No more half way upgraded systems # yum update bash: yum: command not found # atomic host upgrade Upgrade prepared for next boot # atomic host rollback Successfully reset deployment
- 8. Why rpm-ostree? ● Atomic host would only run containers. ● Atomic update makes more sense for an immutable system. ● Allows reuse of RPMs. ● No need to re-invent wheel on packaging. ● Option to rollback to previous state (old good state).
- 9. How rpm-ostree works? ● Fiilesystem is read-only except /var and /etc ● All data (e.g. containers) are unchanged on upgrade. ● /etc gets updated through a 3-way merge.
- 10. /usr/bin/atomic ● Coherent entry point : manage host and containers with the atomic command. ● Fill gaps in Linux container implementations. – e.g. “atomic install foo” can install a container with its k8s configuration and/or systemd unit file. – “atomic run” grabs the LABEL “run” with its all command line details. – It can serve as metadata for containers for different use cases
- 11. Cockpit ● Server manager for administrating Linux servers via web browser. ● Designed to be multi-server ● Support for managing containers, Kubernetes. ● http://cockpit-project.org/
- 12. Want to try? ● ISOs are available for CentOS and Fedora Atomic Host. ● Available in public clouds. ● For Vagrant users – vagrant init fedora/23-atomic-host – vagrant init centos/atomic-host
- 13. Any Questions for Atomic Host? Website: projectatomic.io IRC: #atomic on Freenode
- 14. Containers are great, but it is not just one container.
- 15. In real life applications are composed of multiple containers (Micro-services?)
- 16. But how to define a multi-container application configuration without distributing instructions and files to the end-user ?
- 17. We have docker compose , kubernetes configuration files, but is it enough?
- 18. The application also goes through different stage
- 19. Metadata changes for each stage.
- 20. Nulecule ● A specification ● Container technology independent ● Provide a simple, flexible way to describe a multi-container application, including all dependencies.
- 21. Understanding Nulecule ● Graph – Directed acyclic graph to define application dependencies/components.
- 22. Understanding Nulecule ● Parametrization – Values/information for deployment – Default values (Can be overridden by answers.conf) – Each component has its own parameters – Supports variable substitution, regular expression etc
- 23. Understanding Nulecule ● Answers.conf – Porvides answers to question defined by prarameters – Override default values of parameters (e.g. for different environment)
- 24. Understanding Nulecule ● Providers – e.g. Kubernetes, OpenShift, Docker Compose, Mesos, Docker – Metadata for orchestrators/providers
- 25. A complete Nulecule Spec
- 26. Atomic App ● Nulecule app installer ● At this moment only supports docker run time ● It performs all actions required to run the application by reading the Nulecule spec. – Downloading all required docker images – Communicating to providers etc
- 27. Using Atomic App ● As a docker image ● Use atomicapp base image to build nulecule-ized applications ● Running a nulecule-ized applications – $ atomic run projectatomic/helloapache ● Uses /usr/bin/atomic labels – $ grep Run Dockerfile RUN="docker run -it --rm ${OPT1} --privileged -v `pwd`:/atomicapp -v /run:/run -v /:/host --net=host --name ${NAME} -e NAME=${NAME} -e IMAGE=${IMAGE} ${IMAGE} -v ${OPT2} run ${OPT3} ${IMAGE}"
- 29. Nulecule-library
- 30. Get involved ● https://github.com/projectatomic/nulecule ● https://github.com/projectatomic/nulecule-libr ary ● https://github.com/projectatomic/atomicapp ● #nulecule on Freenode ● Mailing List: container-tools@redhat.com
- 32. Thank you :-) Any questions please? Contact me: @lalatenduM on Twitter lalatenduM on Freenode